java非递归实现树状结构

/**
* 两层循环实现建树
*
* @param treeNodes 传入的树节点列表
* @return
*/
public static List bulid(List treeNodes) {

	List<TreeNode> trees = new ArrayList<TreeNode>();

	for (TreeNode treeNode : treeNodes) {

		if ("0".equals(treeNode.getParentId())) {
			trees.add(treeNode);
		}

		for (TreeNode it : treeNodes) {
			if (it.getParentId() == treeNode.getId()) {
				if (treeNode.getChildren() == null) {
					treeNode.setChildren(new ArrayList<TreeNode>());
				}
				treeNode.getChildren().add(it);
			}
		}
	}
	return trees;
}

public static void main(String[] args) {
TreeNode treeNode1 = new TreeNode(“1”,“广州”,“0”);
TreeNode treeNode2 = new TreeNode(“2”,“深圳”,“0”);

    TreeNode treeNode3 = new TreeNode("3","天河区",treeNode1);
    TreeNode treeNode4 = new TreeNode("4","越秀区",treeNode1);
    TreeNode treeNode5 = new TreeNode("5","黄埔区",treeNode1);
    TreeNode treeNode6 = new TreeNode("6","石牌",treeNode3);
    TreeNode treeNode7 = new TreeNode("7","百脑汇",treeNode6);


    TreeNode treeNode8 = new TreeNode("8","南山区",treeNode2);
    TreeNode treeNode9 = new TreeNode("9","宝安区",treeNode2);
    TreeNode treeNode10 = new TreeNode("10","科技园",treeNode8);


    List<TreeNode> list = new ArrayList<TreeNode>();

    list.add(treeNode1);
    list.add(treeNode2);
    list.add(treeNode3);
    list.add(treeNode4);
    list.add(treeNode5);
    list.add(treeNode6);
    list.add(treeNode7);
    list.add(treeNode8);
    list.add(treeNode9);
    list.add(treeNode10);

    List<TreeNode> trees = bulid(list);
        System.out.println("循环tree--------"+trees);
}

static class TreeNode {
private String id;

private String parentId;

private String name;

private List<TreeNode> children;

public TreeNode(String id, String name, String parentId) {
    this.id = id;
    this.parentId = parentId;
    this.name = name;
}
public TreeNode(String id, String name, TreeNode parent) {
    this.id = id;
    this.parentId = parent.getId();
    this.name = name;
}


public String getParentId() {
    return parentId;
}

public void setParentId(String parentId) {
    this.parentId = parentId;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getId() {
    return id;
}

public void setId(String id) {
    this.id = id;
}

public List<TreeNode> getChildren() {
    return children;
}

public void setChildren(List<TreeNode> children) {
    this.children = children;
}

@Override
public String toString() {
    return "TreeNode{" +
            "id='" + id + '\'' +
            ", parentId='" + parentId + '\'' +
            ", name='" + name + '\'' +
            ", children=" + children +
            '}';
}

}